[R] Mass 'identify' on 2d-plot
ka4alin at yandex.ru
Sun Jan 8 08:19:53 CET 2006
Barry Rowlingson Ð¿Ð¸ÑÐµÑ:
> Evgeniy Kachalin wrote:
>> What is ability in R to graphically (per mouse) define some area and
>> to select all the cases felt in it?
>> 'identify' is OK for 5-10 cases, but what if cases=1000?
> You can use 'locator' to let the user click a number of points to
> define a polygon, and then use one of the point-in-polygon functions
> provided by one of the spatial packages to work out whats in your polygon.
> Look at splancs, spatstat, sp - pretty much anything beginning with
> 'sp' - on CRAN.
> In splancs you can just do:
> poly = getpoly()
> - which lets the user draw a polygon on screen, then:
> inPoly = inpip(xypts,poly)
> points(xypts[inpip,], pch=19,col="red")
> and that will plot the selected points in solid red dots.
> I don't think there's a way to draw a freehand figure on an R plot, you
> have to go click, click, click, and draw straight lines.
I don't get what is 'xypts' in this case... One step earlier i've
plotted plot(y~x,data=dat). What is xypts?
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